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1.	Nordebo, Sven, et al. (författare) Fisher information analysis and preconditioning in electrical impedance tomography 2010 Ingår i: Journal of Physics: Conference Series 224 (2010), 1742-6588. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; , s. 012057- Konferensbidrag (refereegranskat)abstract An adjoint field approach is used to formulate a general numerical framework for Fisher information based sensitivity analysis in electrical impedance tomography. General expressions are given for the gradients used in standard least squares optimization, i.e., the Jacobian related to the forward problem, and it is shown that these gradient expressions are consistent with commonly used electrode models such as the shunt model and the complete electrode model. By using the adjoint field formulations together with a variational analysis, it is also shown how the computation of the Fisher information can be integrated with the gradient calculations used for optimization. It is furthermore described how the Fisher information analysis and the related sensitivity map can be used in a preconditioning strategy to obtain a well balanced parameter sensitivity and improved performance for gradient based quasi-Newton optimization algorithms in electrical impedance tomography. Numerical simulations as well as reconstructions based on experimental data are used to illustrate the sensitivity analysis and the performance of the improved inversion algorithm in a four-electrode measurement set-up.
2.	Kamiya, Noriaki, et al. (författare) On $(\epsilon,\delta)$-Freudenthal Kantor triple systems and anti-structurable algebras with certain conditions 2012 Ingår i: Journal of Physics : Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 346 Konferensbidrag (refereegranskat)abstract In this paper we discuss a characterization of anti-structurable algebras in connection with their relation with $(-1,-1)$-Freudenthal Kantor triple systems.
3.	Sturesson, Peter, 1981-, et al. (författare) Thermomechanical stability and integrability of an embedded ceramic antenna with an integrated sensor element for wireless reading in harsh environments 2013 Ingår i: Journal of Physics: Conference Series. - London : IOP Publishing. - 1742-6588 .- 1742-6596. Konferensbidrag (refereegranskat)abstract This paper reports on the design, manufacturing and evaluation of a small, wirelessly powered and read resonating antenna circuit with an integrated pressure sensor. The work aims at developing miniature devices suitable for harsh environments, where high temperature prevents the use of conventional, silicon-based microdevices. Here, the device is made of alumina with platinum as conducting material. Ceramic green tapes were structured using high-precision milling, metallized using screen printing, and subsequently laminated to form stacks before they were sintered. The device's frequency shift as a function of temperature was studied up to 900°C. The contributions to the shift both from the thermomechanical deformation of the device at large, and from the integrated and, so far, self-pressurized sensor were sorted out. A total frequency shift of 3200 ppm was observed for the pressure sensor for heating over the whole range. Negligible levels of thermally induced radius of curvature were observed. With three-point bending, a frequency shift of 180 ppm was possible to induce with a curvature of radius of 220 m at a 10 N load. The results indicate that a robust pressure sensor node, which can register pressure changes of a few bars at 900°C and wirelessly transmit the signal, is viable.
4.	Boutachkov, P., et al. (författare) Isomer and Beta-decay Spectroscopy of Tz=1 Isotopes Below the N=Z=50 Shell Gap 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 312:9 Tidskriftsartikel (refereegranskat)abstract The RISING setup at the GSI-FRS facility was used to investigate the isomer and beta decays in N~Z~50 Cd, Ag and Pd isotopes. A preliminary analysis of the data has revealed new results on the Tz=1, 94Pd, 96Ag and 98Cd isotopes. In 94Pd a new high-spin isomer was observed, whilst in 96Ag 3 new isomeric states were identified, including core-excited states. In 98Cd a new high-energy isomeric γ-ray transition is observed, thus enabling us to confirm the previous spin assignment for the core-excited 12+ isomer.
5.	Guastalla, G., et al. (författare) Analysis and Results of the 104Sn Coulomb Excitation Experiment 2014 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 533:1 Konferensbidrag (refereegranskat)abstract The analysis of the Coulomb excitation experiment conducted on 104Sn required a strict selection of the data in order to reduce the large background present in the gamma-ray energy spectra and identify the gamma-ray peak corresponding to the Coulomb excitation events. As a result the B(E2; 0 + -> 2+) value could be extracted, which established the downward trend towards 100Sn and therefore the robustness of the N=Z=50 core against quadrupole excitations.
6.	Wadsworth, R., et al. (författare) Spin-gap Isomer in 96Cd 2012 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 381:1 Tidskriftsartikel (refereegranskat)abstract Evidence has been obtained for the existence of the long predicted 16+ spin-gap isomer in 96Cd. The decay of the isomer was identified and studied following the use of an 850 MeV/u beam of 124Xe impinging on a Be target and the fragment recoil separator at the GSI Laboratory. Gamma decays from the fragments were detected using the RISING gamma ray array, in its stopped beam configuration, plus a silicon active stopper. The data obtained have been compared with shell model predictions, which indicate that the isoscalar neutron-proton interaction plays a key role in the formation of the isomer.
7.	Ghasempour, Farideh, 1981, et al. (författare) Multidimensional turbulence spectra – identifying properties of turbulent structures 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 318:4, s. 042022- Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Development of models for several phenomena occurring in turbulent single and multiphase flows requires improved description and quantification of the turbulent structures. This is needed since often the phenomena are very fast or nonlinear. Previously the authors have presented experimental measurements that show that the breakup of bubbles and drops in turbulence is due to interaction with single turbulent vortices. Hence, it is not sufficient to use average turbulence properties when developing models for CFD simulation of engineering applications. In this paper the results from analysis of individual turbulent structures are presented. Results from analysis of the turbulent kinetic energy in turbulent structures, using Eulerian vortex identification methods, are presented. The amount of turbulent kinetic energy associated with a coherent vortex defined using different vortex identification methods is quantified. It is shown that the peak turbulent kinetic energy is located near the edge of the region identified as coherent, making the analysis challenging and development of models difficult. However, detailed analysis of a small number of coherent vortices from LES of turbulent pipe flow reveals new information about their life history. The growth (i.e. entrainment of the surrounding liquid), enstrophy, lifetime, and energy of a specific coherent vortex are tracked over time.
8.	Gustafsson, Anders, et al. (författare) GaAs-based Nanowires Studied by Low-Temperature Cathodoluminescence 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 326, s. 012042-012042 Konferensbidrag (refereegranskat)abstract We present cathodoluminescence data of nanowires (NWs) grown using size-selected gold particles as seeds. The NWs have a GaAs core with a diameter of 50 nm and a length of several mu m. The NWs in this study were generally covered with a shell of AlGaAs. With increasing growth temperature, the emission intensity increases significantly. From a variety of growth conditions, we conclude that the exposed sides of the NWs during growth play an important role in the emission intensity. The diffusion of carriers was studied by inserting a segment of GaInAs in GaAs NWs. By capping the NWs with an AlGaAs shell, we observe a tenfold increase in the diffusion length along the core.
9.	Kómár, A, et al. (författare) Interaction of electromagnetic waves and suprathermal electrons in the near-critical electric field limit 2012 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 401:1 Konferensbidrag (refereegranskat)abstract The velocity-space anisotropy of suprathermal electron distributions is a source of free energy that may destabilize plasma waves through a resonant interaction between the waves and the energetic electrons. In this work we use a suprathermal electron distribution appropriate for the case when the accelerating electric field is near-critical and we investigate the frequencies, wave numbers and propagation angles of the most unstable waves using a general dispersion relation. It is shown that if the electric field is sub-critical, the anisotropy is not enough to drive electromagnetic waves unstable, as the Landau damping of the waves overwhelms the drive through the anomalous Doppler resonance. In the case when the electric field is supercritical, two types of electromagnetic waves will be destabilized, the electron-whistler and the extraordinary electron wave. The number of electrons for destabilization of the latter is several orders of magnitude lower than for the electron-whistler wave. Consequently, the threshold for destabilization of the extraordinary electron wave is much lower.
10.	Puig von Friesen, Marc, et al. (författare) Artificial damping in the Kadanoff-Baym dynamics of small Hubbard chains 2010 Ingår i: Progress in Nonequilibrium Green's Functions IV (Journal of Physics: Conference Series). - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 220, s. 012016-012016 Konferensbidrag (refereegranskat)abstract We perform a comparative study of exact and approximate time-evolved densities in small Hubbard chains. The approximate densities are obtained via many-body perturbation theory (Hartree-Fock, 2(nd) Born, GWand T-matrix approximations) within the framework of the time-dependent Kadanoff-Baym equations. Benchmarking approximate results against exact ones allows us to address two rather fundamental issues in the non equilibrium dynamics of strongly correlated systems. I) A characterisation of the performance of several standard MBAs in the non-equilibrium regime. Having a definite notion of how good a specific MBA can be is highly relevant to its application to cases (typically, infinite systems) where exact solutions are not available. Our results show that the T-matrix approximation is overall superior to the other MBAs, at all electron densities. II) A scrutiny of the whole idea of Many Body Perturbation Theory in the Kadanoff-Baym sense, when applied to finite systems. The surprising outcome of our study is that during the time evolution, the KBE develop an unphysical steady state solution. This is a genuinely novel feature of the time-dependent KBE, i.e. is not inherited from possible limitations/approximations in the calculation of the initial state. Our extensive numerical characterisation gives robust evidence that the problem occurs in general, whenever MBPT is applied to finite systems, and approximate self energies based upon infinite partial summations are used. We also offer some more conceptual and general consideration on the dependence of this behaviour on the number of particles and system size. This is followed by our conclusions and glimpses of future work.
11.	Rosen, Bengt-Göran, 1962, et al. (författare) Topographic modelling of haptic properties of tissue products 2014 Ingår i: Journal of Physics: Conference Series. - Bristol : IOP Publishing. - 1742-6588 .- 1742-6596. ; 483:1 Konferensbidrag (refereegranskat)abstract The way a product or material feels when touched, haptics, has been shown to be a property that plays an important role when consumers determine the quality of products For tissue products in constant touch with the skin, softness becomes a primary quality parameter. In the present work, the relationship between topography and the feeling of the surface has been investigated for commercial tissues with varying degree of texture from the low textured crepe tissue to the highly textured embossed- and air-dried tissue products. A trained sensory panel at was used to grade perceived haptic «roughness». The technique used to characterize the topography was Digital light projection (DLP) technique, By the use of multivariate statistics, strong correlations between perceived roughness and topography were found with predictability of above 90 percent even though highly textured products were included. Characterization was made using areal ISO 25178-2 topography parameters in combination with non-contacting topography measurement. The best prediction ability was obtained when combining haptic properties with the topography parameters auto-correlation length (Sal), peak material volume (Vmp), core roughness depth (Sk) and the maximum height of the surface (Sz). © Published under licence by IOP Publishing Ltd.
12.	Stråhlman, Christian, et al. (författare) Angle-resolved time-of-flight spectroscopy applied to multi-bunch operation at MAX-lab: a design study 2013 Ingår i: IOP Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 425 Konferensbidrag (refereegranskat)abstract Angle-resolved time-of-flight (ARTOF) spectrometers have found use in a number of applications, including ARPES. However, the fundamental requirement of an external start trigger matching the read-out time of the instrument limits its usability at many storage rings. Hitherto all reported experiments have been performed at storage rings capable of running in single-bunch mode. To eliminate this restriction, we propose a method where a pulsed electronic gate is introduced to allow for ARTOF usage at normal multi-bunch operation of the MAX II storage ring. This paper will show the working principle and outline the design for this technique.
13.	Thunnissen, Marjolein, et al. (författare) BioMAX: The Future Macromolecular Crystallography Beamline at MAX IV 2013 Ingår i: 11th International Conference on Synchrotron Radiation Instrumentation (SRI 2012). - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 425 Konferensbidrag (refereegranskat)abstract This paper describes the preliminary design of the BioMAX beamline at the 3 GeV ring of the MAX IV facility, focusing on the optics and x-ray beam performance. The MAX IV facility will include two storage rings with 1.5 GeV and 3.0 GeV electron energy and a linac serving both as injector for the two rings and feeding a short pulse facility. BioMAX is one of the first seven beamlines funded at the MAX IV facility. It is a multipurpose high-throughput beamline for macromolecular crystallography. The beamline aims to be robust and simple to operate with a beam benefiting from the properties of the MAX IV 3 GeV ring. However it does not aim at the smallest beam or crystal sizes since it is foreseen that it will be complemented with a microfocus beamline aiming at a beam size of 1 mu m. The beamline experiment setup will be highly automated, both in terms of sample handling hardware and data analysis, including feedback to the data collection. The BioMAX beamline is planned to be in operation in 2016.
14.	Häggström, Lennart, et al. (författare) Thickness dependent crystallographic transition in Fe/Ni multilayers 2010 Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 217, s. 012112- Tidskriftsartikel (refereegranskat)abstract The crystallog. transition between bcc- and fcc-structures has been studied in Fe/Ni multilayers with Moessbauer spectroscopy and X-ray diffraction. Layered structures have been confirmed and the structures depends both on individual layer thickness and the ratio of the constituents. Two sets of samples are made: the Fe layer thickness kept const. to 12 monolayer (ML) and 24ML, while the Ni layer thicknesses varied from 3 to 12ML. When the Ni layer is thin, the Fe/Ni multilayers have the bcc phase. When the thickness of Ni layer reaches 6ML and larger, a gradual transition to the fcc phase occurs. Moessbauer spectroscopy studies confirm the existence of a magnetic Fe bcc phase with in-plane magnetization in all samples, two magnetic fcc phases with fields of 28 T and 10 T and small amts. of nonmagnetic fcc phases in the thicker films. The obsd. behavior can be attributed to the existence of two types of interfaces which are not necessary overlapping each other: An elemental interface between Fe and Ni and a structural interface between fcc and bcc phases. [on SciFinder(R)]
15.	Shestopalov, Yury, 1953-, et al. (författare) Inverse scattering in guides 2012 Ingår i: Journal of Physics, Conference Series. - Philadelphia : Institute of Physics Publishing (IOPP). - 1742-6588 .- 1742-6596. ; 346, s. 012019-1-012019-13 Tidskriftsartikel (refereegranskat)abstract We present statements and a method of solution to the inverse scattering problem of reconstructing permittivity of a dielectric inclusion in a 2D or 3D waveguide from thetransmission characteristics. The approach employs a volume singular integral equation (VSIE) method. The unique solvability of VSIE is established. The inverse problem is solved by themethod of iterations applied to VSIE; the convergence of the method is proved
16.	Khrennikov, Andrei, 1958- (författare) Measurement problem : from De Broglie to theory of classical random fields interacting with threshold detectors 2013 Ingår i: Journal of Physics, Conference Series. - : Institute of Physics (IOP). - 1742-6588 .- 1742-6596. ; 442, s. Article ID: 012011- Tidskriftsartikel (refereegranskat)abstract The quantum measurement problem as was formulated by von Neumann in 1933 can be solved by going beyond the operational quantum formalism. In our "prequantum model" quantum systems are symbolic representations of classical random fields. The Schrödinger's dynamics is a special form of the linear dynamics of classical fields. Measurements are described as interactions of classical fields with detectors. Discontinuity, the "collapse of the wave function", has the trivial origin: usage of threshold type detectors. The von Neumann projection postulate can be interpreted as the formal mathematical encoding of the absence of coincidence detection in measurement on a single quantum system, e.g., photon's polarization measurement. Our model, prequantum classical statistical field theory (PCSFT), in combination with measurements by threshold detectors satisfies the quantum restriction on coincidence detections: the second order coherence is less than one (opposite to all known semiclassical and classical feld models). The basic rule of quantum probability, the Born's rule, is derived from properties of prequantum random felds interacting with threshold type detectors. Comparison with De Broglie's views to quantum mechanics as theory of physical waves with singularities is presented.
17.	Macias, Raul, et al. (författare) Performance of the Load-in-the-Loop Single Op-Amp Voltage Controlled Current Source from the Op-Amp Parameters 2010 Ingår i: Journal of Physics: Conference Series. - : Institute of Physics Publishing Ltd.. - 1742-6596 .- 1742-6588. Konferensbidrag (refereegranskat)abstract In recent years, Electrical Bioimpedance (EBI) methods have gained importance. These methods are often based on obtaining impedance spectrum in the range of β-dispersion, i.e. from a few kHz up to some MHz. To measure EBI a constant current is often injected and the voltage across the tissue under study (TUS) is recorded. Due to the performance of the current source influences the performance of the entire system, in terms of frequency range, several designs have been implemented and studied. In this paper the basic structure of a Voltage-Controlled Current Source (VCCS) based on a single Op-Amp in inverter configuration with a floating load, known as load-in-the-loop current source, is revisited and studied deeply. We focus on the dependence of the output impedance with the circuit parameters, i.e. the feedback resistor and the inverter-input resistor, and the Op-Amp main parameters, i.e. open loop gain, CMRR and input impedance. After obtaining the experimental results and comparing to the theoretical and simulated ones, they confirm the design under study can be a good solution for multi-frequency wideband EBI applications because of higher values of the output impedance than 100kΩ at 1MHz are obtained. Furthermore, an enhancement of the basic design, using a current conveyor as a first stage, is proposed, studied and implemented.
18.	Yanson, I. K., et al. (författare) Vortex-like state observed in ferromagnetic contacts 2010 Ingår i: Journal of Physics: Conference Series. - : Institute of Physics Publishing (IOPP). - 1742-6588 .- 1742-6596. ; 200:5, s. 1-4 Tidskriftsartikel (refereegranskat)abstract Point-contacts (PC) oﬀer a simple way to create high current densities, 109 A/cm 2and beyond, without substantial Joule heating. We have shown recently (Nano Letters, 7(2007) 927) that conductivity of nanosized PCs between a normal and ferromagnetic metalsexhibits bi-stable hysteretic states versus both bias current and external magnetic ﬁeld – theeﬀect typical for spin-valve structures. Here we report that apart from the bi-stable state athird intermediate-resistance state is occasionally observed. We interpret this state as due toa spin-vortex in the PC, nucleated either by Oersted ﬁeld of the bias current and/or by thecircular geometry of PC. The observed three-level-states in the PC conductivity testify that theinterface spins are both weakly coupled to the spins in the bulk and have depressed exchangeinteraction within the surface layer.
19.	Alcorta, M., et al. (författare) Properties of resonances in 12C above the triple-alpha threshold 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 312:SECTION 9, s. Art. no. 092013- Konferensbidrag (refereegranskat)abstract A complete kinematics study of the 10B(3He, pααα) and the 11B(3He, dααα) reactions has been performed to study the multi-particle break-up of 12C resonances above the triple-alpha threshold. The values of energy and widths of some states has been improved, and in states of natural parity partial branches of decay through the ground state of 8Be have been extracted. The influence of the "ghost" of the 8Be ground state has been taken into account in order to clarify the partial branches.
20.	Bergman, Martin, 1985-, et al. (författare) Surface design methodology : challenge the steel 2013 Ingår i: Metrology and Properties of Engineering Surfaces, 2013. - Bristol, UK : Institute of Physics Publishing (IOPP). ; 483:1, s. Art. no. 012013- Konferensbidrag (refereegranskat)abstract The way a product or material is experienced by its user could be different depending on the scenario. It is also well known that different materials and surfaces are used for different purposes. When optimizing materials and surface roughness for a certain something with the intention to improve a product, it is important to obtain not only the physical requirements, but also the user experience and expectations. Laws and requirements of the materials and the surface function, but also the conservative way of thinking about materials and colours characterize the design of medical equipment. The purpose of this paper is to link the technical- and customer requirements of current materials and surface textures in medical environments. By focusing on parts of the theory of Kansei Engineering, improvements of the companys' products are possible. The idea is to find correlations between desired experience or «feeling» for a product, -customer requirements, functional requirements, and product geometrical properties -design parameters, to be implemented on new improved products. To be able to find new materials with the same (or better) technical requirements but a higher level of user stimulation, the current material (stainless steel) and its surface (brushed textures) was used as a reference. The usage of focus groups of experts at the manufacturer lead to a selection of twelve possible new materials for investigation in the project. In collaboration with the topical company for this project, three new materials that fulfil the requirements -easy to clean and anti-bacterial came to be in focus for further investigation in regard to a new design of a washer-disinfector for medical equipment using the Kansei based Clean ability approach CAA. © Published under licence by IOP Publishing Ltd.
21.	Borge, M. J. G., et al. (författare) Scattering of the halo nucleus 11Li and its core 9Li on 208Pb at energies around the Coulomb barrier 2012 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 381:1, s. Art. no. 012085- Konferensbidrag (refereegranskat)abstract The first measurement of the elastic scattering of the halo nucleus 11Li and its core 9Li on 208Pb at energies around the Coulomb barrier is presented. The 11Li reaction showed a large cross section for the breakup channel, even at energies well below the barrier. The analysis of the 11Li + 208Pb scattering data in terms of the continuum-discretized coupled-channel calculations indicates that the effect of the coupling to the breakup channels produces a strong suppression of the elastic cross section at energies above and below the barrier. This effect is mainly due to the strong Coulomb coupling to the dipole states in the low-lying continuum of 11Li.
22.	Bruce, A. M., et al. (författare) Beta Decay of 102Y Produced in Projectile Fission of 238U 2012 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 381 Tidskriftsartikel (refereegranskat)abstract The population of 102Zr following the β decay of 102Y produced in the projectile fission of 238U at the GSI facility in Darmstadt, Germany has been studied. 102Y is known to ß decay into 102Zr via two states, one of high spin and the other low spin. These states preferentially populate different levels in the 102Zr daughter. In this paper the intensities of transitions in 102Zr observed are compared with those from the decay of the low-spin level studied at the TRISTAN facility at Brookhaven National Laboratory and of the high-spin level studied at the JOSEF separator at the Kernforschungsanlage Jülich.
23.	Ceberg, Crister (författare) A note on the interpretation of the gamma evaluation index 2013 Ingår i: 7th International Conference on 3D Radiation Dosimetry (IC3DDose). - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 444, s. 012082-012082 Konferensbidrag (refereegranskat)abstract The gamma evaluation method has become the gold standard for the comparison between measured and calculated absorbed dose distributions. However, test criteria and failure rate tolerance levels have hitherto normally been based on empirical evidence, rather than rigorous statistical analysis. In this work, it is proposed that the gamma-evaluation method could be reinterpreted such that the absorbed dose difference and distance-to-agreement criteria are replaced by the standard deviations of the associated uncertainties. By comparison between absorbed dose calculations and simulated measurements for clinically realistic test cases in 1D and 2D, it is then shown that the resulting squared gamma distribution follows a chi-squared distribution with one degree of freedom. This result can be used to test the statistical significance of measured deviations, and to determine proper failure rate tolerance levels in clinical radiotherapy quality control.
24.	Ceberg, Sofie, et al. (författare) Evaluation of breathing interplay effects during VMAT by using 3D gel measurements 2013 Ingår i: 7th International Conference on 3D Radiation Dosimetry (IC3DDose). - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 444, s. 012098-012098 Konferensbidrag (refereegranskat)abstract Respiratory motion during dynamic radiotherapy may affect the absorbed dose distribution both by dose-reducing smoothing and by more complicated interplay effects. In this study we present a novel method to determine the relative importance of these two effects. For the two dynamic deliveries studied in this work, the expected target dose reduction due to the smoothing effect was estimated by measurements convolved by the motion function. Remaining absorbed dose differences were attributed to interplay effects between the motion of the gel phantom and the movement of the modulating MLC leaves during modulated arc radiotherapy. The total dosimetric effect due to breathing motion and dynamic MLC motion during VMAT delivery resulted in an average of about 4% target dose reduction. Comparing with only the smoothing effect, the average difference was decreased to around 1%, and the remaining distribution was attributed to interplay effects. Although the interplay effects were small compared to the smoothing effect, the standard deviations of 1.4-2.3% (1SD) were larger than the narrow distribution for repeated stationary measurement with a standard deviation between 0.5-0.9% (1SD).
25.	Ceberg, Sofie, et al. (författare) Radiotherapy delivery during motion 2010 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 250 Tidskriftsartikel (refereegranskat)abstract This paper discusses the 3D dosimetric consequences of radiotherapy delivery during two kinds of motion, (i) the respiratory motion by the patient and (ii) the motion by the gantry while rotating around the patient. Respiratory motion primarily compromises treatments in the thorax and abdomen regions. Several strategies to reduce respiratory motion effects have been developed or are under development. The organ motion could for instance be measured and incorporated in the treatment planning, or adapted to by using respiratory gating and tumour-tracking delivery techniques. Gantry motion is involved in various forms of intensity-modulated arc-therapy techniques. The purpose is to increase the modulation by simultaneously varying the MLC positions, the rotation speed of the gantry, and the dose rate during the treatment. The advantage of these techniques is the increased possibility to deliver a high absorbed dose to the target volume while minimizing the dose to normal tissues. However, the dosimetric uncertainties associated with motion, small fields and steep dose gradients, has to be evaluated in detail, and this requires adequate true 3D dose-verification tools.
26.	Ceberg, Sofie, et al. (författare) Tumor-tracking radiotherapy of moving targets; verification using 3D polymer gel, 2D ion-chamber array and biplanar diode array 2010 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 250:1, s. 235-239 Tidskriftsartikel (refereegranskat)abstract The aim of this study was to carry out a dosimetric verification of a dynamic multileaf collimator (DMLC)-based tumor-tracking delivery during respiratory-like motion. The advantage of tumor-tracking radiation delivery is the ability to allow a tighter margin around the target by continuously following and adapting the dose delivery to its motion. However, there are geometric and dosimetric uncertainties associated with beam delivery system constraints and output variations, and several investigations have to be accomplished before a clinical integration of this tracking technique. Two types of delivery were investigated in this study I) a single beam perpendicular to a target with a one dimensional motion parallel to the MLC moving direction, and II) an intensity modulated arc delivery (RapidArc®) with a target motion diagonal to the MLC moving direction. The feasibility study (I) was made using an 2D ionisation chamber array and a true 3D polymer gel. The arc delivery (II) was verified using polymer gel and a biplanar diode array. Good agreement in absorbed dose was found between delivery to a static target and to a moving target with DMLC tracking using all three detector systems. However, due to the limited spatial resolution of the 2D array a detailed comparison was not possible. The RapidArc® plan delivery was successfully verified using the biplanar diode array and true 3D polymer gel, and both detector systems could verify that the DMLC-based tumor-tracking delivery system has a very good ability to account for respiratory target motion.
27.	Charity, R. J., et al. (författare) Two-proton decay of the 6Be ground state and the double isobaric analog of 11Li 2013 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 420:1 Konferensbidrag (refereegranskat)abstract Two-proton decay is discussed in a number of light isobaric multiplets. For the lightest two-proton emitter, 6Be, the momentum correlations between the three decay products were measured and found to be consistent with quantum-mechanical three-cluster-model calculations. Two-proton decay was also found for two members of the A=8 and A=11 quintets. Finally, a third member of the A=11 sextet, the double isobaric analog of the halo nucleus 11Li in 11B was observed by its two-proton decay.
28.	Cherkashyna, Nataliia, et al. (författare) High energy particle background at neutron spallation sources and possible solutions 2014 Ingår i: International Workshop on Neutron Optics and Detectors (NOP&D 2013) 2–5 July 2013, Munich, Germany. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 528, s. 012013-012013 Konferensbidrag (refereegranskat)abstract Modern spallation neutron sources are driven by proton beams similar to GeV energies. Whereas low energy particle background shielding is well understood for reactors sources of neutrons (similar to 20 MeV), for high energies (100s MeV to multiple GeV) there is potential to improve shielding solutions and reduce instrument backgrounds significantly. We present initial measured data on high energy particle backgrounds, which illustrate the results of particle showers caused by high energy particles from spallation neutron sources. We use detailed physics models of different materials to identify new shielding solutions for such neutron sources, including laminated layers of multiple materials. In addition to the steel and concrete, which are used traditionally, we introduce some other options that are new to the neutron scattering community, among which there are copper alloys as used in hadronic calorimeters in high energy physics laboratories. These concepts have very attractive energy absorption characteristics, and simulations predict that the background suppression could be improved by one or two orders of magnitude. These solutions are expected to be great benefit to the European Spallation Source, where the majority of instruments are potentially affected by high energy backgrounds, as well as to existing spallation sources.
29.	Cooper-Jensen, Carsten, et al. (författare) "m=1" coatings for neutron guides 2014 Ingår i: International Workshop on Neutron Optics and Detectors (NOP&D 2013) 2–5 July 2013, Munich, Germany. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 528, s. 012005-012005 Konferensbidrag (refereegranskat)abstract A substantial fraction of the price for a supermirror neutron guide system is the shielding, which is needed because of the gamma radiation produced as a result of neutron absorption in the supermirror layers. Traditional coatings have been made of nickel-titanium heterostructures, but Ni and Ti also have a fairly high absorption cross section for cold and thermal neutrons. We examine a number of alternatives to Ni as part of a study to reduce the gamma radiation from neutron guides. Materials such as diamond and Be have higher neutron scattering density than Ni, smaller absorption cross section, and when a neutron is absorbed they emit gamma photons with lower energies. We present reflectivity data comparing Ni with Be and preliminary results from diamond coatings showing there use as neutron guide coatings. Calculations show that Be and diamond coatings emit two orders of magnitude fewer gamma photons compared to Ni, mainly because of the lower absorption cross section.
30.	DiJulio, Douglas, et al. (författare) Optimization of multi-channel neutron focusing guides for extreme sample environments 2014 Ingår i: International Workshop on Neutron Optics and Detectors (NOP&D 2013) 2–5 July 2013, Munich, Germany. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 528, s. 012006-012006 Konferensbidrag (refereegranskat)abstract In this work, we present and discuss simulation results for the design of multi-channel neutron focusing guides for extreme sample environments. A single focusing guide consists of any number of supermirror-coated curved outer channels surrounding a central channel. Furthermore, a guide is separated into two sections in order to allow for extension into a sample environment. The performance of a guide is evaluated through a Monte-Carlo ray tracing simulation which is further coupled to an optimization algorithm in order to find the best possible guide for a given situation. A number of population-based algorithms have been investigated for this purpose. These include particle-swarm optimization, artificial bee colony, and differential evolution. The performance of each algorithm and preliminary results of the design of a multi-channel neutron focusing guide using these methods are described. We found that a three-channel focusing guide offered the best performance, with a gain factor of 2.4 compared to no focusing guide, for the design scenario investigated in this work.
31.	DiJulio, Douglas, et al. (författare) Sub-barrier Coulomb excitation of Sn-107 2012 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 381, s. 012073-012073 Konferensbidrag (refereegranskat)abstract A Coulomb excitation experiment in inverse kinematics has been carried out at the REX-ISOLDE facility in order to study the properties of low-lying excited states in Sn-107. The measured gamma ray spectrum has been compared with predicted gamma ray spectra from a combined shell-model and GOSIA analysis. In this approach, a set of matrix elements, generated within the shell-model framework, based on a realistic nucleon-nucleon interaction and a set of single-particle energies relative to Sn-100, is used as input. Comparison between the calculated and predicted spectra can be used to help identify the placement of the single-neutron states in Sn-101. In particular, the results can potentially provide clues on the ordering of the two lowest-lying orbits; the g(7/2) and d(5/2) states.
32.	Dochev, Dimitar Milkov, 1981, et al. (författare) Superconducting IF biasing circuit for low-noise cryogenic applications 2010 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 234:4 Konferensbidrag (refereegranskat)abstract A planar superconducting circuit designed for use in low-noise cryogenic applications is presented. The circuit is a bias-T combined with a 4–8 GHz impedance matching circuitry, which employs entirely planar design with a novel layout. The proposed and tested circuitry is intended to be used with a SIS mixer and incorporates a double section transformer based on microstrip line technology with a total impedance transformation of 5:1 within the frequency band. One of the transformer sections employs a three-line coupled line, which also serves as a DC block capacitor. The microstrip lines were manufactured using superconducting Nb metallization, which provides a conduction loss-free solution at the operation temperature of 4 K. S-parameter measurements at 4 K temperature were performed and found to be in a good agreement with the simulations. The device measured return loss is better than −10 dB within the frequency band. Furthermore, the circuit was tested as a part of 385 – 500 GHz double sideband heterodyne SIS receiver demonstrating a flat noise temperature response of 80 – 90 K over the entire IF band of 4 – 8 GHz.
33.	Dochev, Dimitar Milkov, 1981, et al. (författare) The influence of aging and annealing on the properties of Nb/Al-AlOx/Nb tunnel junctions 2010 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 234:4 Konferensbidrag (refereegranskat)abstract This paper presents results of our studies on aging and annealing properties of Nb/Al-AlOx/Nb junctions. We performed a long room temperature aging with subsequent annealing at different temperatures up to 250°C. A distinct change of the junctions' normal-state resistance has been observed. Aging at room temperature results in a slight decrease of the normal-state resistance combined with improved junction quality, characterised by a better subgap-to-normal resistance ratio. Annealing at moderate temperatures in air increases the normal-state resistance and leads to improvement of the junction quality followed by degradation at higher annealing temperatures. The increase in the junction quality after long-term aging at room temperature is attributed to relaxation of the internal junction structure and interfaces, thus, resulting in a lower density of interface traps. The deterioration at higher annealing temperatures could be a consequence of diffusion processes at the Al/Nb interface. We observe a sufficiently clear difference between the behaviour of preliminary aged and newly fabricated junctions after annealing: for the aged high-quality junction, the degradation was negligible up to temperatures of 200°C, while non-aged junctions show a much faster and abrupt degradation at lower annealing temperatures.
34.	Edvardsson, Anneli, et al. (författare) The effect of systematic set-up deviations on the absorbed dose distribution for left-sided breast cancer treated with respiratory gating 2013 Ingår i: 7th International Conference on 3D Radiation Dosimetry (IC3DDose). - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 444, s. 012099-012099 Konferensbidrag (refereegranskat)abstract The aim of this study was 1) to investigate interfraction set-up uncertainties for patients treated with respiratory gating for left-sided breast cancer, 2) to investigate the effect of the inter-fraction set-up on the absorbed dose-distribution for the target and organs at risk (OARs) and 3) optimize the set-up correction strategy. By acquiring multiple set-up images the systematic set-up deviation was evaluated. The effect of the systematic set-up deviation on the absorbed dose distribution was evaluated by 1) simulation in the treatment planning system and 2) measurements with a biplanar diode array. The set-up deviations could be decreased using a no action level correction strategy. Not using the clinically implemented adaptive maximum likelihood factor for the gating patients resulted in better set-up. When the uncorrected set-up deviations were simulated the average mean absorbed dose was increased from 1.38 to 2.21 Gy for the heart, 4.17 to 8.86 Gy to the left anterior descending coronary artery and 5.80 to 7.64 Gy to the left lung. Respiratory gating can induce systematic set-up deviations which would result in increased mean absorbed dose to the OARs if not corrected for and should therefore be corrected for by an appropriate correction strategy.
35.	Enders, J., et al. (författare) Reactions with polarized electrons and photons at low momentum transfers at the superconducting Darmstadt electron linear accelerator S-DALINAC 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 295:1, s. Art. no. 012152- Konferensbidrag (refereegranskat)abstract A source of polarized electrons has been installed at the superconducting Darmstadt electron linear accelerator S-DALINAC. Experiments with polarized electrons from 100 keV to about 80 MeV are expected to commence in early 2011. This contribution summarizes the status of the polarized source as well as ongoing preparations for the experimental program with polarized beams. In particular, we present results on unpolarized test experiments of the, 234,238U(γ,f) reactions and considerations for the 2D(e→,e′p) and reactions.
36.	Eriksson, Mikael, et al. (författare) The MAX IV Facility 2013 Ingår i: 11th International Conference on Synchrotron Radiation Instrumentation (SRI 2012). - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 425 Konferensbidrag (refereegranskat)abstract The MAX IV synchrotron radiation facility is currently being constructed in Lund, Sweden. The accelerator park consists of a 3 GeV linac injector and 2 storage rings operated at 1.5 and 3 GeV respectively. The linac injector will also be used for the generation of short Xray pulses. Close to 30 straight sections will be available for IDs at the rings. The three machines mentioned above are described below with some emphasis on the effort to create a very small emittance in the 3 GeV ring. Some unconventional technical solutions imposed by the emittance minimisation are discussed.
37.	Eriksson, Ola, et al. (författare) Analysis of long distance wakes of Horns Rev I using actuator disc approach 2014 Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 555:1 Tidskriftsartikel (refereegranskat)abstract The wake recovery behind the Horns Rev wind farm is analysed to investigate the applicability of Large Eddy Simulations (LES) in combination with an actuator disc method (ACD) for farm to farm interaction studies. Periodic boundary conditions on the lateral boundaries are used to model the wind farm (as infinitely wide), using only two columns of turbines. The meteorological conditions of the site are taken into account by introducing wind shear and pre-generated synthetic turbulence to the simulation domain using body forces. Simulations are carried out to study the power production and the velocity deficit in the farm wake. The results are compared to the actual power production as well as to wind measurements at 2 km and 6 km behind the wind farm. The simulated power production inside the farm shows an overall good correlation with the real production, but is slightly overpredicted in the most downstream rows. The simulations overpredict the wake recovery, namely the wind velocity, at long distances behind the farm. Further studies are needed before the presented method can be applied for the simulation of long distance wakes. Suggested parameters to be studied are the development of the turbulence downstream in the domain and the impact of the grid resolution.
38.	Fariborz, Shahriar (författare) Free vibration of a rod undergoing finite strain 2012 Ingår i: Journal of Physics, Conference Series. - : Institute of Physics (IOP). - 1742-6588 .- 1742-6596. ; 382:1 Tidskriftsartikel (refereegranskat)abstract The finite strain longitudinal free vibration of a rod is studied. Utilizing second Piola-Kirchhoff stress and Green strain tensors, the equation of motion is written in terms of displacement in reference configuration. Three different types of homogenous boundary conditions may be considered for the rod, leading to three nonlinear eigenvalue problems. The series solutions with three terms satisfying the boundary conditions are utilized and the relationships between amplitudes of vibration are obtained by means of the Galerkin method. The backbone curves are drawn and the internal resonance between different modes of vibration is analyzed.
39.	Fogelström, Mikael, 1963, et al. (författare) Tunneling limit of heavy-fermion point contacts 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 273 Konferensbidrag (refereegranskat)abstract We present results for a multichannel tunneling model that describes point-contact spectra between a metallic tip and a superconducting heavy-fermion system. We calculate tunneling spectra both in the normal and superconducting state. In point-contact and scanning tunneling spectroscopy many heavy-fermion materials, like CeCoIn5, exhibit an asymmetric differential conductance, dI/dV, combined with a strongly suppressed Andreev reflection signal in the superconducting state. For Andreev reflection to occur a junction has to be in the highly transparent limit. Here we focus on the opposite limit, namely that of low transparency leading to BCS-like dI/dV curves. We discuss the consequences of a multichannel tunneling model for CeCoIn5 assuming itinerant electron bands and localized f electrons.
40.	Fomichev, A. S., et al. (författare) Status of the ACCULINNA-2 project at FLNR 2012 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 337:1, s. Art. no. 012025- Konferensbidrag (refereegranskat)abstract The project of a new and more powerful in-flight fragment separator ACCULINNA-2 at U-400M cyclotron in FLNR, JINR planned to build in addition to the existing separator ACCULINNA is presented. The new separator will provide high intensity RIBs in the lowest energy range (5÷50 MeV/nucleon) which is attainable for in-flight separators. The possibilities for the astrophysics studies at the proposed device are presented. ACCULINNA-2 separator is planned to be constructed in the years 2010-2015. The current status of the project is reported.
41.	Giovannella, Simona, et al. (författare) U boson searches at KLOE 2011 Ingår i: Journal of Physics, Conference Series. - : Institute of Physics (IOP). - 1742-6588 .- 1742-6596. ; 335:1, s. 012067- Tidskriftsartikel (refereegranskat)abstract The existence of a secluded gauge sector could explain several puzzling astrophysical observations. This hypothesis can be tested at low energy e + e âˆ’ colliders such as DAÎŠNE. Preliminary results obtained with KLOE data and perpectives for the KLOE-2 run, where a larger data sample is expected, are discussed.
42.	Gisselbrecht, Mathieu, et al. (författare) Charge migration and decay of doubly charged ammonia clusters 2012 Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 388:2, s. 022112- Tidskriftsartikel (refereegranskat)abstract The photo-fragmentation of ammonia molecular clusters ionized with soft x-rays is studied for photon energies near the N-1s threshold. The fragmentation is studied with a 3D momentum mass spectrometer to access the energy and angular correlations between fragments. By choosing the cluster sizes below or above the critical size of stable dication, we investigate the coulomb explosion dynamics and the interplay between charge delocalization and mobility of molecules in the clusters.
43.	Gisselbrecht, Mathieu, et al. (författare) Exploring single-photon ionization on the attosecond time scale 2012 Ingår i: XXVII International Conference on Photonic, Electronic and Atomic Collisions (Icpeac 2011), Pts 1-15. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 388, s. 032025-032025 Konferensbidrag (refereegranskat)abstract One of the fundamental processes in nature is the photoelectric effect in which an electron is ripped away from its atom via the interaction with a photon. This process was long believed to be instantaneous but with the development of attosecond pulses (1 as 10(-18) s) we can finally get an insight into its dynamic. Here we measure a delay in ionization time between two differently bound electrons. The outgoing electrons are created via ionization with a train of attosecond pulses and we probe their relative delay with a synchronized infrared laser. We demonstrate how this probe field influences the measured delays and show that this contribution can be estimated with a universal formula, which allows us to extract field free atomic data..
44.	Gottardo, A., et al. (författare) Isomers in Neutron-rich Lead Isotopes Populated via the Fragmentation of 238U at 1 GeV A 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 312 Tidskriftsartikel (refereegranskat)abstract Neutron-rich nuclei beyond N = 126 in the lead region were populated by fragmenting a 238U beam at 1 GeV A on a Be target and then separated by the Fragment Separator (FRS) at GSI. Their isomeric decays were observed, enabling study of the shell structure of neutron-rich nuclei around the Z=82 shell closure. Some preliminary results are reported in this paper.
45.	Grizolli, Walan, et al. (författare) Use of astigmatic re-focusing at HP-XPS end-station 2013 Ingår i: 11th International Conference on Synchrotron Radiation Instrumentation (SRI 2012). - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 425 Konferensbidrag (refereegranskat)abstract In this paper we present the refocusing optics for the new high pressure photoelectron spectroscopy (HP-XPS) branch line at MAX-lab, based on a plane grating monochromator with vertically collimated beam. For the HP-XPS instrument, the required spot size is dictated by the small geometric acceptance of the HP-XPS electron energy analyzer. Whereas a pair of bendable mirrors in a KB configuration has some advantages as refocusing elements, we have studied whether similar performance can be achieved with a single non-bendable mirror. In this solution, however, the need for strong horizontal magnification results in a strong vertical magnification and into a very asymmetric image, the height being just a fraction of the width. We have studied through an analytical geometrical model and ray tracing simulations the use of astigmatism to increase the vertical beam size up to the geometric acceptance of the detector. As a result the vertical beam size at sample plane is mostly determined by the photon angular distribution and is not dependent on the exit slit aperture size. In addition the vertical beam size can be controlled by the grating c(ff) parameter, making possible to adjust the photon density and minimize sample damage by the radiation.
46.	Grumer, Jon, et al. (författare) Magnetic field induced transition rates in Ne- and Be-like ions for plasma diagnostics and E1M1 two-photon decay rate determination 2014 Ingår i: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 488, s. 152005-152005 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract We report on theoretical results of magnetic field induced transitions (MITs) in Ne- and Be-like ions without nuclear spin for two applicalions. Firstly, MITs are promising candidates in the determination of magnetic fields in plasmas. In our work on Ne-like ions we present accurate theoretical MIT rates for 2p(6 1)S(O) - 2p(5)3s 3P(O),2 [11. Purthermore, for Be-like ions, it has been proposed to extract the rate of the BIM1 two-photon transition 2s(2 1)S(O) - 2s2p P-3(O) by measuring the lifetime of the 'Po state using a storage ring, which involves an external magnetic field. The MIT rates are carefully evaluated and shown to be of the same order as the ElMI rates [2].
47.	Hamamoto-Kuroda, Ikuko (författare) Shell structure of weakly-bound and resonant neutrons 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 267:1, s. 012005-012005 Konferensbidrag (refereegranskat)abstract The systematic change of shell structure in both weakly bound and resonant neutron one-particle levels in nuclei towards the neutron drip line is exhibited, solving the coupled equations derived from the Schrodinger equation in coordinate space with the correct asymptotic behaviour of wave functions for r -> infinity. The change comes from the behaviour unique in the one-particle motion with low orbital angular momenta compared with that with high orbital angular momenta. The observed deformation of very neutron-rich nuclei with N greater than or similar to 20 in the island of inversion is a natural result of this changed shell structure, while a possible deformation of neutron-drip-line nuclei with N approximate to 51, which are not yet observed, is suggested.
48.	Henningson, Måns, 1964 (författare) Six-dimensional (2,0) theory on tori 2013 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 462:1 Konferensbidrag (refereegranskat)abstract The six-dimensional (2,0) theories are a comparatively new and rather abstract type of quantum theory with important relations both to supersymmeric Yang-Mills theory in lower dimensions and to string- and M-theory in higher dimensions. After a short introduction to these theories, we focus on the case when they are considered on flat tori [1] [2]. In particular, we give an example of how their ground state degeneracies can be computed, and also briefly discuss the spectrum of BPS-states. Finally, we comment on the automorphic transformation properties of the partition function of such a theory under the mapping class group of a six-torus.
49.	Holmqvist, Cecilia, 1975, et al. (författare) Critical charge and spin Josephson currents through a precessing spin 2012 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 400:2, s. 022027- Konferensbidrag (refereegranskat)abstract We present a theoretical study of two superconductors coupled over a spin. The spin is treated classically and is assumed to precess with the Larmor frequency due to an external magnetic field. The precession results in spin-dependent Andreev scattering and a non- equilibrium population of the Andreev levels. Charge and spin currents at zero temperature were studied previously [1]. Here, we focus on the critical current as well as the corresponding spin currents at finite temperatures. At finite temperatures, the spin precession can enhance the supercurrent by a population redistribution. The enhancement leads to a modified current- phase relation and a non-monotonous critical current as function of temperature. This non- monotonous behavior is accompanied by a corresponding change in spin-transfer torques acting on the precessing spin and leads to the possibility of using temperature as a means to tune the back-action on the spin.
50.	Håakansson, L., et al. (författare) A numerical method for the study of solid-liquid mass transfer in turbulent flows 2011 Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 318:SECTION 2 Konferensbidrag (refereegranskat)abstract A numerical method for the study of high-Schmidt number mass transfer close to solid boundaries is presented. Computational Fluid Dynamics with the Large Eddy Simulations and the dynamic Smagorinsky model for the subgris scale stress tensor were used. Periodic boundary conditions were used to obtain proper boundary conditions for the LES simulation. A fine mesh was used in the bulk of the flow and a extremely fine mesh (y + = 1/40) on a part of the surface where the diffusional flux was evaluated. Model validation shows that the teoretical y + dependences were obtained for the fluctuations paralell to the surface and a somewhat lower y + depencence was obtained for the much smaller perpendicular fluctuation. It is also shown that DNS resolution was obtained in the extremely fine mesh. The usefuleness of the modeling method is exemplified with a simulation of species concentration and by particle tracking the influence of the turbulence on the fluid elements near the walls at y +

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